Scholar and philosopher, born at Coblenz, 16 March, 1805; died at Munich, 9 May, 1861. His father, Johann Claudius von Lasaulx, was a distinguised architect; his uncle, Johann Joseph Görres (q.v.), was the fiery champion of Catholic liberties; and the young Ernst became imbued with an enthusiam for the Catholic Faith and for liberty. He first studied at Bonn (1824-30), and later took up classical philology and philosophy at Munich, attaching himself in particular to Schelling, Görres, and Baader, and then spent four years travelling through Austria, Italy, Greece, and Palestine, visiting the places most famous in the history of civilization, both pagan and Christian. His voyage to Athens was made as a member of the suite of Prince Otto of Wittelsbach (Bavaria), who had been elected King of the Hellenes. On his return to his native land he took the doctor's degree at Kiel, in 1835, presenting a dissertation entitled "De mortis dominatu in veteres, commentatio theologica-philosophica", and was appointed dozent in classical philology at the University of Wurzburg, where he exercised a deep and far-reaching influence on the youth of the university. Meanwhile he married Julie Baader, daughter of the Munich philosopher, Franz Baader.

Upon the arrest (20 November, 1837) of Clemens August, Archbishop of Cologne, whose forcible detention in the fortress of Minden by the order of Prussian Government caused a great stir in Catholic circles both at home and abroad, Lasaulx wrote to his uncle, Görres, calling upon him to protest against the arbitrary act of the "military Government of Berlin against the Archbishop of Cologne". This was the impulse that was responsible for Görres's celebrated "Athanasius". At the same time Lasaulx himself issued the controversial pamphlet "Kritische Bemerkungen über die Kölner Sache", a bold attack on the Prussian Government and the diplomat Josias von Bunsen. In the autumn of 1844 Lasaulx was appointed professor of philology and aesthetics at the University of Munich, despite the vigorous efforts of the Würzburg senate to secure his continued services there. At Munich he quickly became famous as a magnetic and stimulating teacher. When his influence effected the downfall of the minister Abel, the senate of the University applauded his action, but King Louis, on the other hand, vented his displeasure by dismissing Lasaulx from office ( 28 February, 1847). Demonstrations on the part of the students followed, resulting in the dismissal of eight other members of the University teaching staff. In 1848 Lasaulx, with three of his former colleagues, was elected to the National Assembly at Frankfort, where he identified himself with the Conservative group and again and again eloquently defended the liberties of the Catholic Church among the intellectual elite of Germany.

King Maximilian II having at length yielded to the petition of the Munich students to reinstate Lasaulx and the other expelled professors (15 March, 1849), Lasaulx resumed his work as a philosophical writer. In the same year he was elected a member of the Bavarian Chamber of Deputies, where, until his death, his masterly ability in all political controversies found energetic expression. Soon after his death, four of his works were placed on the Index; it was found that in them he had erred on the side of effacing the distinction between the common human religious element in heathenism and the theological expression of Christian revelation. Several years earlier, however, he had declared that, should any errors be found in his works, he would freely submit to the judgment of the Church.